In the specific technical field of the manufacture of light alloy wheels, of aluminium alloy in particular, the mechanical machining which is mainly required on these metal parts comprises turning and drilling in accordance with predetermined working cycles.
These working cycles generally comprise rather short cycle times, of the order of a few minutes, in which the effect of the time during which tools are moved (otherwise known as the “changeover time”) and the time for loading/unloading the workpieces is rather substantial in comparison with the actual time for which the machine tools are working in the overall cycle time. By way of example it may be noted that this may amount to even 30% and more of the machining cycle time in the case of cycle times of the order of approximately 1 minute.
It is also obvious that as the specified cycle times are reduced (as a result, for example, of reduced working times for the removal of turnings), because the changeover and loading/unloading times remain substantially unchanged this effect increases in proportion, penalizing the overall productivity of the machining equipment.